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[Nocturnal noninvasive ventilation of children and adolescents with neuromuscular diseases: effect on sleep and symptoms].
AIM: Sleep disordered breathing (SDB) is an inevitable complication of progressive neuromuscular disorders (NMD). Aim of the study was to prospectively investigate the impact of three months of non-invasive ventilation (NIV) on sleep and SDB-associated symptoms in children and adolescents with advanced NMD. METHODS: Twenty-two patients (11.1 +/- 4.3 years) with symptomatic SDB were enrolled in the study and evaluated with polysomnography and a symptom questionnaire. Twenty patients were treated with pressure assisted ventilation during sleep. The impact of NIV on SDB, sleep and symptoms was re-evaluated after 3 months of NIV. RESULTS: In 2/22 patients, after adenotomy, SDB was no longer demonstrable. In the remaining 20 patients NIV improved SDB (Respiratory Disturbance Index 1.8 +/- 1.6 vs. 9.2 +/- 4.5/h; minimal SpO2 91 +/- 3 vs. 79 +/- 12%). Three months of treatment resulted in shortened sleep latency (17 +/- 13 vs. 42 +/- 38 minutes), improved sleep efficiency (95 +/- 3 vs. 89 +/- 9%) and less EEG-arousals (11 +/- 5 vs. 22 +/- 9/h, p < 0.001 for all). Sleep-stage proportion did not change. Patients reported significant improvements of sleep quality, morning headaches, mood, concentration and daytime sleepiness (p < 0.001 for all). CONCLUSIONS: In children with NMD intermittent nocturnal NIV results in objective and subjective improvements of sleep quality and symptoms associated with SDB.
Direct measurement of IGF-I and IGFBP-3 in bronchoalveolar lavage fluid from idiopathic pulmonary fibrosis.
Idiopathic pulmonary fibrosis (IPF) is characterized by the rearrangement of extracellular matrix and progressive increase in the amount of fibrotic tissue in the lung. IGF-I is a potent profibrogenic molecule and its bioavailability is dependent on at least 6 binding proteins called IGFBPs. Among these, IGFBP-3 is the most represented in serum and in different connective tissues. The purpose of this study was to identify and characterize IGFBP-3 in bronchoalveolar lavage (BAL) fluids. We studied 11 patients with IPF and 6 normal subjects by performing baseline pulmonary function test and BAL. IGF-I and IGFBP-3 were measured by RIA in BAL and serum. No significant differences were observed between serum IGF-I and IGFBP-3 from IPF patients and normal subjects. Instead, the direct measurement in BAL revealed a significant increase of IGF-I and IGFBP-3 in IPF patients compared to normal subjects. BAL IGF-I and IGFBP-3 concentrations were significantly related to inspiratory vital capacity (IVC) and carbon dioxide partial pressure (PaCO2): the higher the value of IVC and the lower the value of PaCO2, the higher the level of IGF-I and IGFBP-3. In conclusion, IGFBP3 and IGF-I could be important local mediators of IPF. Their direct measurement in BAL in IPF patients could be used as a clinical marker of the disease, since high levels of IGFBP-3 and IGF-I in BAL are associated to the initial phase of the disease.
Noninvasive positive pressure ventilation in acute respiratory failure of chronic obstructive pulmonary disease.
Noninvasive positive pressure ventilation (NPPV) has reemerged as an effective strategy for reducing morbidity and mortality associated with acute exacerbations of chronic obstructive pulmonary disease (COPD). During acute respiratory failure, dynamic hyperinflation, intrinsic PEEP, and increased airway resistance result in a mechanical workload that exceeds inspiratory muscle capacity. NPPV provides augmentation of alveolar ventilation and respiratory muscle rest. Observational, cohort, and more recently, randomized controlled trials have demonstrated the ability of NPPV to increase the need for endotracheal intubation and decrease complications and mortality. NPPV performs better in COPD patients without significant comorbid illness. It should be initiated during COPD exacerbations if arterial pH is less than 7.35 or if the patient is severely distressed. Pressure support ventilation (10-20 cmH2O) via face mask is likely the optimal technique and, when successful, results in rapid clinical improvement.
Effect of inspiratory flow waveform on work on endotracheal tubes: a model analysis.
OBJECTIVE: This model analysis aimed to predict the impact of different inspiratory flow wave-forms, i. e., constant, sinusoidal, and two linearly decreasing flows, on the resistive work (Wres) performed on endotracheal tubes. DESIGN: Model analysis. RESULTS: Model analysis predicts that: (i) minimal Wres is obtained with the constant flow; (ii) for any given tidal volume/inspiratory duration (V(T)/T(I), mean inspiratory flow), Wres increases with decreasing tube size; (iii) for any given inspiratory flow waveform, Wres increases with increasing V(T)/T(I), being lowest with constant flow. CONCLUSIONS: These findings have major clinical implications: at any given ventilator setting, not only the size of the endotracheal tube but also the inspiratory flow waveform must be taken into account to interpret the values of Wres and hence of the total work of breathing.
Association of orofacial with laryngeal and respiratory motor output during speech.
Speech motor coordination most likely involves synaptic coupling among neural systems that innervate orofacial, laryngeal, and respiratory muscles. The nature and strength of coupling of the orofacial with the respiratory and laryngeal systems was studied indirectly by correlating orofacial speeds with fundamental frequency, vocal intensity, and inspiratory volume during speech. Fourteen adult subjects repeated a simple test utterance at varying rates and vocal intensities while recordings were obtained of the acoustic signal and movements of the upper lip, lower lip, tongue, jaw, rib cage, and abdomen. Across subjects and orofacial speed measures (14 subjects x 4 structures), significant correlations were obtained for fundamental frequency in 42 of 56 cases, for intensity in 35 of 56 cases, and for inspiratory volume in 14 of 56 cases. These results suggest that during speech production there is significant neural coupling of orofacial muscle systems with the laryngeal and respiratory systems as they are involved in vocalization. Comparisons across the four orofacial structures revealed higher correlations for the jaw relative to other orofacial structures. This suggests stronger connectivity between neural systems linking the jaw with the laryngeal and respiratory systems. This finding may be relevant to the frame/content theory of speech production, which suggests that the neural circuitry involved in jaw motor control for speech has evolved to form relatively strong linkages with systems involved in vocalization.
Increased inspiratory pressure for reduction of atelectasis in children anesthetized for CT scan.
BACKGROUND: Atelectasis is more frequent and more severe in children anesthetized for CT scan than it is in children sedated for CT scan. OBJECTIVE: To determine the effect of increased inspiratory pressure on atelectasis during chest CT in anesthetized children. MATERIALS AND METHODS: Atelectasis on chest CT was assessed by two observers in three groups of patients. Group A comprised 13 children (26 lungs) anesthetized at inspiratory pressures up to and including 25 cm H2O. Group B included 11 children anesthetized at inspiratory pressures > or =30 cm H2O. Group C included 8 children under deep sedation. RESULTS: Atelectasis was significantly more severe in group A than in groups B and C. There was no significant difference between groups B and C. CONCLUSION: An inspiratory pressure of 30 cm H2O is recommended for children anesthetized for CT scan of the chest.
The effects of different inspiratory muscle training intensities on exercising heart rate and perceived exertion.
This study investigated the relationship between the intensity of an inspiratory muscle training programme and its effect on respiratory muscle strength, exercising heart rate, and ratings of perceived exertion. A total of 66 subjects were randomly assigned to one of three groups. One group trained at 100% of maximum inspiratory pressure (MIP) for 6 weeks (MAX, n=22). A second group performed 6 weeks of inspiratory muscle training at 80% of MIP (SUB, n=21) and a third control group received no inspiratory training (CON, n=23). Both the MAX and SUB training groups improved MIP relative to the control group [32 (19) cmH(2)O, P=0.01; 37 (25) cmH(2)O, P=0.001, respectively]. A significant decrease in heart rate [-6 (9) beats min(-1), P=0.02] and rating of perceived exertion [-0.5 (1.4), P=0.04] was observed for the MAX group only. It is concluded that 6 weeks of both MAX and SUB training were sufficient to improve inspiratory muscle strength. However, exercising heart rate and perceived exertion decreased with MAX training only.
Lung deposition of budesonide from turbuhaler in asthmatic children.
UNLABELLED: The aim of our study was to evaluate the effect of age on lung deposition of radiolabelled budesonide, delivered as a dry powder via Turbuhaler to asthmatic children. A group of 23 asthmatic children, aged 6 to 16 years, with relatively stable asthma inhaled 99mTc-labelled budesonide from a dry powder inhaler (Turbuhaler). Body and lung deposition was assessed using a gamma camera. The mean (range) median peak inspiratory flow during inhalation was 65 1 x min(-1) (45 to 76 1 x min(-1)). Mean (range) total lung deposition of 99mTc-labelled budesonide, expressed as a percentage of the metered dose, was 29.1% (15.6-47.2%) and was positively and significantly correlated with age, height and peak inspiratory flow. CONCLUSION: Total lung deposition of radiolabelled budesonide from a dry powder inhaler (Turbuhaler), is age dependent in children with moderate asthma. However, lung deposition is still satisfactory, even in younger children with lower peak inspiratory flows.
The effect of an oral contraceptive on the pulmonary functions.
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Respiratory dynamics and speech intelligibility in speakers with generalized dystonia.
This study investigated aspects of respiratory function, during quiet breathing and monologue, in six adult dystonic subjects and compared the findings to a control group of four neurologically intact adults. Additionally, breathing dynamics were compared with speech intelligibility. Respiratory inductive plethysmography was used to assess breathing rate, periodicity of the breathing pattern, and inspiratory lung volume. Ear oximetry was used to assess arterial blood oxygen saturation. Speech intelligibility was rated by a panel of five judges. Breathing patterns differed between groups; the dystonic subjects showed a faster breathing rate, less rhythmic breathing pattern, decreased lung volume, and apnealike periods accompanied by a decrease in arterial blood oxygen saturation. These differences were observed during quiet breathing and monologue. Decreased speech intelligibility was strongly related to differences in breathing dynamics.
Induced respiratory change in asthmatic children.
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Effect of rib cage or abdomen compression at iso-lung volume on breathing pattern.
In anesthetized rabbits a small compression of the rib cage (RC) caused a marked increase of breathing frequency (f), a marked reduction of expiratory duration (Te), a reduction of inspiratory duration (Ti) and tidal volume (VT), while an equal decrease of lung volume produced by abdominal compression(AC) caused a smaller increase of f and no change of Ti, and a slight increase of VT. Similar results occurred when normal end-expiratory volume was maintained during compression. The phenomena disappeared after bilateral vagotomy, whereas persisted after cordotomy in T1. Similar results occurred in dogs (with the exception that VT decreased during AC), whereas in cats only RC increased f by shortening Te. RC caused a marked increase of discharge in 11 out of 19 irritant receptor fibers, whereas AC caused an increase only in 2. In most of the pulmonary stretch receptor fibers the change of activity produced by compression paralleled the lung volume change. The effects of vagal cooling on Ti, Te and the VT-Ti relationship with and without compression suggest irritant receptors as responsible for the different ventilatory pattern during RC and AC.
Changes in the Breuer-Hering reflexes following rostral pontine lesion.
The lung stretch reflex characteristics of unanesthetized decerebrate cats were determined using servo-controlled lung volume changes before and after bilateral lesion of the dorsolateral rostral pons in the region of nucleus parabrachialis medialis (NPBM). During the inspiratory phase the time-dependent threshold curve for inspiratory inhibition by lung inflation was shifted to larger volumes after lesion with no change in the constant describing its rate of decay. During the expiratory phase the gain of the inflation reflex was found to be increased by lesion, but otherwise to remain qualitatively the same. Deflations during the expiratory phase revealed a prolonged central inhibitory state with reduced rate of decay late in expiration. It is concluded that with intact vagi structures in the region of NPBM constitute but one of at least three sources of inspiratory inhibition, feedback derived from peripheral lung stretch receptors and from caudal pontine or medullary neurons also being involved. It is also concluded that the structures in the vicinity of NPBM affect the switching mechanisms differently during the two phases of the cycle: During inspiration they contribute a tonic threshold lowering input to the inspiratory "off-switch"; whereas, during expiration they provide inspiratory-facilitatory influences late in the phase.
Study of intrapulmonary gas mixing in man by simultaneous wash-out of helium and sulfur hexafluoride.
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The effect on breathing of abruptly stopping carotid body discharge.
In bilaterally vagotomized, decerebrate or pentobarbitone anaesthetized cats, intense carotid body discharge (FET O2 ca. 0.075) was abruptly removed by injections centrally of 100% O2-equilibrated Ringer into both external carotid arteries. In an inspiration the injections usually shortened that inspiration, reduced its volume and prolonged the immediately following expiration. Early in expiration they prolonged that expiration, but later in expiration they shortened it. The inspiratory results can be reconciled with von Euler's model of the inspiratory off-switch if the off-switch acts early because a reduction in chemoreceptor input lowers its threshold more rapidly than it reduces the input to it. The threshold falls to half of its final value in about one second. The respiratory centres respond to decreases in carotid body activity nearly as quickly as to increases, and expiration can be altered independently of the preceding inspiration. We present a simple model of the control of expiratory duration.
Temporal variation in the VT-TI relationship in humans.
The variation with time of the relationship between tidal volume (VT) and inspiratory duration (TI) was assessed by analysis of 34 breathing sequences, nominally of 300 breath duration, during eupnea and hypercapnic hyperpnea in 6 human subjects. Two approaches were used: (1) each sequence was divided into consecutive 50-breath blocks and standard regression techniques used to characterize VT as a function of TI; and (2) a piecewise linear regression technique was applied to cluster consecutive breaths into regression regimes. Analysis of covariance was used with the results of both approaches to determine the likelihood that a single regression line was adequate to describe the entire data set. Similar results obtained regardless of the approach used. In only 4 of the 34 experiments would the hypothesis of regression slope homogeneity be accepted (P greater than 0.05) using the clustering approach; in 27 experiments, it was indicated that the regression slope estimates of VT on TI should not be considered homogeneous. Changes in the VT-TI slope were not correlated with changes in mean levels of VT, TI, minute ventilation (V), mean inspiratory flow (VT/TI), nor alveolar PCO2 (PACO2). Thus it is apparent that the VT-TI relation cannot be considered temporally invariant, but changes with time over periods ranging from less than 20 to more than 100 breaths.